Method and apparatus for performing fractional subframe transmission

ABSTRACT

Embodiments of the disclosure provide a method and apparatus for performing fractional subframe transmission. The method may comprise: in response to detecting that a channel becomes available, determining a target position from at least one potential position predefined in a subframe; and performing the fractional subframe transmission from the target position.

CLAIM FOR PRIORITY

This application is a Continuation of U.S. patent application Ser. No.16/041,313 filed on Jul. 20, 2018, which is a continuation applicationof U.S. patent application Ser. No. 15/644,147, filed Jul. 7, 2017 (nowU.S. Pat. No. 10,063,356, Issued Aug. 28, 2018), which is a continuationapplication of U.S. patent application Ser. No. 15/302,817, filed Oct.7, 2016, (now U.S. Pat. No. 9,888,497, Issued Feb. 6, 2018) which is a371 of International Application PCT/CN2015/071898, filed Jan. 30, 2015,all of which are incorporated by reference herein.

FIELD OF THE INVENTION

Embodiments of the present invention generally relate to communicationtechniques. More particularly, embodiments of the present inventionrelate to a method and apparatus for performing fractional subframetransmission.

BACKGROUND OF THE INVENTION

In 3rd Generation Partnership Project (3GPP), the network structure andvarious technologies needed for a terminal's movement between a 3GPPwireless communication network and a Wireless Local Area Network (WLAN)network are called interworking WLAN. The multi-mode wirelesscommunication technology has evolved to use multiple wirelesscommunication technologies at the same time. The use of multiplewireless communication technologies simultaneously thereby increasestransfer rates per unit time or improves the reliability of theterminal.

In wireless communication, the spectrum is very rare resource. Alicensed band represents a frequency band that is exclusively licensedto a specific operator to provide specific wireless services. On theother hand, an unlicensed band represents a frequency band that is notallocated to a specific operator, but is opened so that all entitiesmeeting the predefined requirements may use the frequency band.

In some regions in the world, unlicensed band technologies need to abideto certain regulations, for example, Listen-Before-Talk (LBT), andchannel bandwidth occupancy requirements. LBT results in an uncertaintyof channel availability. For instance, an unlicensed band may beavailable at any time during a subframe.

WLAN that uses Wireless Fidelity (WiFi) is the typical wirelesscommunication technology used in the unlicensed band. Time granularityof current Long Term Evolution (LTE) is much larger than that of WiFi,which leads to the low competitive strength of License Assisted Access(LAA) with LBT. As such, fair coexistence between LTE and othertechnologies such as WiFi as well as between LTE operators is expected.

In order to be more competitive in the unlicensed band, there is a needto perform fractional subframe transmission with low signaling overheadand high resource utilization.

SUMMARY OF THE INVENTION

The present invention proposes a solution regarding fractional subframetransmission. Specifically, the present invention provides a method andapparatus for fractional subframe transmission with low signalingoverhead and high resource utilization.

According to a first aspect of embodiments of the present invention,embodiments of the invention provide a method for performing fractionalsubframe transmission. The method may comprise: in response to detectingthat a channel becomes available, determining a target position from atleast one potential position predefined in a subframe; and performingthe fractional subframe transmission from the target position. Themethod may be performed at a transmitter.

According to a second aspect of embodiments of the present invention,embodiments of the invention provide a method for performing fractionalsubframe transmission. The method may comprise: determining a targetposition from at least one potential position predefined in a subframe,the fractional subframe transmission starting at the target position;and receiving the fractional subframe transmission from the targetposition. The method may be performed at a receiver.

According to a third aspect of embodiments of the present invention,embodiments of the invention provide an apparatus for performingfractional subframe transmission. The apparatus may comprise: a firstdetermining unit configured to in response to detecting that a channelbecomes available, determine a target position from at least onepotential position predefined in a subframe; and a performing unitconfigured to perform the fractional subframe transmission from thetarget position. The apparatus may be implemented at a transmitter.

According to a fourth aspect of embodiments of the present invention,embodiments of the invention provide an apparatus for performingfractional subframe transmission. The apparatus may comprise: a seconddetermining unit configured to determine a target position from at leastone potential position predefined in a subframe, the fractional subframetransmission starting at the target position; and a receiving unitconfigured to receive the fractional subframe transmission from thetarget position. The apparatus may be implemented at a receiver.

Other features and advantages of the embodiments of the presentinvention will also be apparent from the following description ofspecific embodiments when read in conjunction with the accompanyingdrawings, which illustrate, by way of example, the principles ofembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are presented in the sense of examples andtheir advantages are explained in greater detail below, with referenceto the accompanying drawings, where

FIG. 1 illustrates a flow chart of a method 100 for performingfractional subframe transmission at a transmitter according to anembodiment of the invention;

FIG. 2 illustrates a flow chart of a method 200 for performingfractional subframe transmission at a transmitter according to anotherembodiment of the invention;

FIG. 3 illustrates a flow chart of a method 300 for performingfractional subframe transmission at a receiver according to anembodiment of the invention;

FIG. 4 illustrates a flow chart of a method 400 for performingfractional subframe transmission at a receiver according to anotherembodiment of the invention;

FIG. 5 illustrates a schematic diagram 500 of fractional subframetransmission according to embodiments of the invention;

FIG. 6 illustrates a schematic diagram 600 of fractional subframetransmission according to embodiments of the invention;

FIG. 7 illustrates a block diagram of an apparatus 700 for performingfractional subframe transmission according to embodiments of theinvention; and

FIG. 8 illustrates a block diagram of an apparatus 800 for performingfractional subframe transmission according to embodiments of theinvention.

Throughout the figures, same or similar reference numbers indicate sameor similar elements.

DETAILED DESCRIPTION OF EMBODIMENTS

The subject matter described herein will now be discussed with referenceto several example embodiments. It should be understood theseembodiments are discussed only for the purpose of enabling those skilledpersons in the art to better understand and thus implement the subjectmatter described herein, rather than suggesting any limitations on thescope of the subject matter.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” when usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the figures.For example, two functions or acts shown in succession may in fact beexecuted concurrently or may sometimes be executed in the reverse order,depending upon the functionality/acts involved.

Embodiments of the present invention are directed to a solution forperforming fractional subframe transmission. The solution may be carriedout between a receiver and a transmitter. In particular, upon detectingthat a channel becomes available, the transmitter may determine a targetposition from at least one potential position predefined in a subframeand perform the fractional subframe transmission from the targetposition. The receiver may determine a target position from the at leastone predefined potential position in a similar way and receive thefractional subframe transmission from the target position. In this way,transmission may be performed without introducing signalling overhead.Meanwhile, once a channel enters an idle state, the transmission maystart from the current subframe, instead of the next subframe. As such,resource utilization is improved.

In embodiments of the present invention, a fractional subframe may referto a subframe for downlink transmission or a subframe for uplinktransmission, wherein one part of the fractional subframe is used fortransmission of control information or data and the other part is notused for the transmission. For example, for a downlink subframecomprising 14 symbols, if only the last 6 symbols are available for inthe downlink transmission while the first 8 symbols are unavailable,this subframe may be considered as a factional subframe.

In the disclosure, the fractional subframe transmission may refer to thetransmission performed on one or more subframes, and at least one of theone or more subframes is a fractional subframe. By way of example, thefractional subframe transmission may comprise various cases, such as thefirst subframe being a fractional subframe, the last subframe being afractional subframe, both the first and the last subframes beingfractional subframes, and the like.

In some embodiments, the fractional subframe transmission may bedownlink or uplink cellular transmission. In downlink transmission, thereceiver may comprise user equipment (UE), such as a terminal, a MobileTerminal (MT), a Subscriber Station (SS), a Portable Subscriber Station(PSS), Mobile Station (MS), or an Access Terminal (AT). Meanwhile, thetransmitter may comprise a base station (BS), such as a node B (NodeB orNB), or an evolved NodeB (eNodeB or eNB). In uplink transmission, thetransmitter may comprise a UE and the receiver may comprise a BS.

According to some other embodiments of the present invention, thefractional subframe transmission may be D2D transmission. In thisregard, the receiver may be a Device-to-Device (D2D) receiver and thetransmitter may be a D2D transmitter.

Embodiments of the present invention may be applied in variouscommunication systems, including but not limited to a Long TermEvolution (LTE) system or a Long Term Evolution Advanced (LTE-A) system.Given the rapid development in communications, there will of course alsobe future type wireless communication technologies and systems withwhich the present invention may be embodied. It should not be seen aslimiting the scope of the invention to only the aforementioned system.

Now some exemplary embodiments of the present invention will bedescribed below with reference to the figures. Reference is first madeto FIG. 1, which illustrates a flow chart of a method 100 for performingfractional subframe transmission at a transmitter according to anembodiment of the invention. The method 100 may be performed at atransmitter, such as a BS, a D2D transmitter, and other suitable device.

The method 100 starts at step S110, in which in response to detectingthat a channel becomes available, a target position is determined fromat least one potential position predefined in a subframe.

According to embodiments of the present invention, a subframe maycomprise a plurality of symbols. By way of example, a subframe may be 1ms and comprise 14 symbols, for example, symbols 0 to 13. A position,such as a potential position, a target position, a current position, anext position, may refer to a time point or a time period in thesubframe. In some embodiments, a position may correspond to an instantin a subframe. As an alternative, a position may correspond to a symbolof a subframe. In this regard, the position may occupy a time period,for example, the time period of a symbol. In the context, a targetposition may refer to a position from which the fractional transmissionmay start, and a potential position may refer to a predefined positionthat is a candidate of the target position.

According to embodiments of the present invention, there may be one ormore potential positions predefined in a subframe. Each of the potentialpositions may correspond to a symbol of the subframe periodically oraperiodically. In some embodiments, the potential positions may compriseevery three symbols, for example, symbols 0, 3, 6, 9 and 12. Forinstance, the potential positions may be set atmod(N,Nd)=x(x∈[0,Nd−1]),  (1)

where N represents the index of a symbol in a subframe, and Ndrepresents the interval between two potential positions and may be aninteger ranged from 1 to the total number of symbols in the subframe,for example 14. According to equation (1), it may be determined that thesmaller the Nd is, the denser the potential positions are. In someembodiments, each symbol in a subframe may be predefined as a potentialposition.

It is to be noted that the above examples are illustrated for example,rather than limitation. It can be appreciated that, in alternativeembodiments, there may be aperiodic configurations of the potentialpositions. For instance, the potential positions may correspond to thesymbols 0, 3, 8 and 12.

According to embodiments of the present invention, Clear ChanelAssessment (CCA) or Extended Clear Chanel Assessment (eCCA) may beperformed. With the CCA/eCCA, the transmitter may detect whether achannel is available. In response to detecting that the channel becomesavailable, the transmitter may determine the target position from one ormore potential positions in several ways. In some embodiments, whether acurrent position is a potential position is detected first. If thecurrent position is a potential position, the potential position may bedetermined as the target position; otherwise, a channel occupationsignal may be transmitted from the current position until a potentialposition and then the potential position may be determined as the targetposition.

At step S120, the fractional subframe transmission is performed from thetarget position.

According to embodiments of the present invention, at step S120, thetransmitter may send an indicator at the target position to a receiver.The indicator may indicate a size of control information of thefractional subframe transmission, for example, the number of symbols ofPhysical Downlink Control Channel (PDCCH). In some embodiments, theindicator may be implemented as Physical Control Format IndicatorChannel (PCFICH), or any other suitable indicator. Upon receiving theindicator, the receiver may know the size of the control information.For example, when the receiver detects PCFICH, it may have the knowledgeof the number symbols of PDCCH. It is to be noted that the above exampleis shown only for illustration purpose, without suggesting anylimitations on the scope of the subject matter described herein. As canbe appreciated, in some embodiments, the control information may beconfigured by higher layer signaling or configured according tospecification(s).

According to embodiments of the present invention, at step S120, thetransmitter may determine the number of available symbols in thesubframe based on the target position, and transmit control informationand data of the fractional subframe transmission from the targetposition based on the number of the available symbols. In someembodiments, the control information may be transmitted on PDCCH, andthe data may be transmitted on Physical Downlink Shared Channel (PDSCH).Details of the embodiments will be described with reference to FIG. 2.

According to embodiments of the present invention, the schedulinginformation associated with each of the potential position may bepreconfigured in advance. When performing the fractional subframetransmission, the transmitter may obtain the preconfigured schedulinginformation associated with the target position, and perform thefractional subframe transmission based on the preconfigured schedulinginformation. As such, upon determining the target position, thetransmitter does not have to spend much time on configuring schedulinginformation associated with the target position. In this way, thefractional subframe transmission may be performed more quickly andefficiently.

FIG. 5 illustrates a schematic diagram 500 of fractional subframetransmission according to embodiments of the invention. FIG. 5exemplarily shows four subframes, subframes 0 to 3. With respect tosubframe 0, there are three potential positions 521, 522 and 523,wherein the first potential position 521 corresponds to the start ofsubframe 0, for example, symbol 0 of subframe 0. CCA/eCCA 501 may startfrom the first potential position 521. During the CCA/eCCA 501, thetransmitter may determine that the channel is available at a position524. Since the position 524 is not a potential position, the transmittermay transmit channel occupation signals from the position 524 until apotential position, for example, the potential position 522, anddetermine the potential position 522 as the target position. Thefactional subframe transmission then may start from the target position,wherein control information may be transmitted on PDCCH at time periods503, 505, 507 and 509, and data may be transmitted on PDSCH at timeperiods 504, 506, 508 and 510.

Reference is now made to FIG. 2, which illustrates a flow chart of amethod 200 for performing fractional subframe transmission at atransmitter according to another embodiment of the invention. The method200 may be considered as a specific implementation of the method 100described above with reference to FIG. 1. However, it is noted that thisis only for the purpose of illustrating the principles of the presentinvention, rather than limiting the scope thereof.

Method 200 begins at step S210, in which a channel is detected asbecoming available.

According to embodiments of the present invention, whether a channel isavailable may be detected in several ways, such as energy detection,carrier sensing, and so on. In some embodiments, strength of energy froma further transmitter may be measured on the channel. The furthertransmitter may be a transmitter that may use the same channel and isdifferent from the transmitter performing the method according toembodiments of the present invention. If the energy strength is notstrong, it may be determined that the channel is idle. In this regard,the energy strength may be compared with a strength threshold. Inresponse to that the measured strength is less than the strengththreshold, the channel may be determined as being available. Thestrength threshold may be a predetermined threshold, which may be setaccording to system requirements, specifications, channel quality, andso on. According to embodiments of the present invention, the strengththreshold may be set as a fixed value or a value that is changeddynamically. It is to be understood that the above example embodimentsare only for the purpose of illustration, without suggesting anylimitations on the subject matter described herein. The strengththreshold may be implemented in any other suitable ways.

Alternatively, the channel availability may be detected based on carriersensing. By way of example, a signalling from a further transmitter maybe detected on the channel. The further transmitter may be a transmitterthat may use the channel and is different from the transmitterperforming the method according to embodiments of the present invention.Based on the signalling, whether the channel is available may bedetermined.

It is to be noted although the above embodiments illustrate a furthertransmitter, there may be a plurality of further transmitters in acommunication system according to embodiments of the present invention.In such embodiments, energy detection and carrier sensing may beperformed with respect to the plurality of further transmitters.

At step S220, whether a current position is a potential position isdetected.

If the current position is a potential position, the flow goes to stepS240, where the potential position is determined as the target position.If the current position is not a potential position, the flow goes tostep S230, where a channel occupation signal is transmitted from thecurrent position until a potential position. Then, the flow goes to stepS240, where the potential position is determined as the target position.

At step S250, a number of available symbols in the subframe aredetermined based on the target position.

In some embodiments, the number of available symbols may be determinedbased on the target position and the total number of symbols in asubframe. By way of example, if there are 14 symbols in one subframe,and if the target position corresponds to the sixth symbol, that is,symbol 5, it may be determined that there are 8 available symbols, i.e.,symbols 6 to 13. For another example, if there are 12 symbols in onesubframe, and if the target position corresponds to the eighth symbol,that is, symbol 7, it may be determined that there are 4 availablesymbols, i.e., symbols 8 to 11.

At step S260, control information and/or data of the fractional subframetransmission are transmitted from the target position based on thenumber of the available symbols.

In some embodiments, if the channel is available in earlier symbols of asubframe, for example, symbol 0 to 6, normal control information, forexample normal PDCCH, may be applied. If the channel is available inlatter symbols of a subframe, for example, symbol 9 to 13, shortenedcontrol information, for example shortened PDCCH, may be applied. In anexemplary embodiment, the normal PDCCH may occupy 3 symbols and theshortened PDCCH may occupy 1 or 2 symbols.

Additionally, in some embodiments, responsive to the number of theavailable symbols is less than or equal to a predetermined threshold,the transmitter may transmit the control information and the data in theavailable symbols of the subframe and a subframe immediately followingthe subframe. In an exemplary embodiment, if the number of the availablesymbols is equal to the size of the control information, the transmittermay transmit the control information in the available symbols of thesubframe and transmit the data in a subframe immediately following thesubframe. In a further exemplary embodiment, if the number of theavailable symbols is less than the size of the control information, thetransmitter may transmit a first part of the control information in theavailable symbols of the subframe and a second part of the controlinformation in a further subframe immediately following the subframe,wherein the first part and the second part constitute the controlinformation. After the control information is transmitted, thetransmitter may transmit the data in the further subframe. According toembodiments of the present invention, the predetermined threshold may beset as a fixed value or a value that is changed dynamically, and may beconfigured by high layer signalling or prescribed by specifications. Inan exemplary embodiment, the predetermined threshold may be set as 3.

FIG. 6 illustrates a schematic diagram 600 of fractional subframetransmission according to embodiments of the invention. FIG. 6exemplarily shows four subframes, subframes 0 to 3. With respect tosubframe 0, there are two potential positions 621 and 622. CCA/eCCA 601may start from the first potential position 621. During CCA/eCCA 601,the transmitter may determine that the channel is available at thepotential position 622. Thus, the potential position 622 may bedetermined as the target position. The factional subframe transmissionthen may start from the target position, wherein control information maybe transmitted on PDCCH at time periods 602, 603 and 605, and data maybe transmitted on PDSCH at time periods 604 and 606. As shown in FIG. 6,the control information is transmitted in the available symbols of thesubframe 0 and its following subframe 1, corresponding to the timeperiods 602 and 603 respectively. After the control information, thedata is transmitted at the time period 604. In particular, the firstpart of the control information is transmitted at the time period 602,and the second part of the control information is transmitted at thetime period 603.

It is to be noted that, the factional subframe transmission may ends ata portion of a subframe or at a full subframe. According to embodimentsshown in FIG. 5, the factional subframe transmission ends at a position525. Thus, a portion of subframe 3 is used for the factional subframetransmission. In this case, both the first subframe (i.e., subframe 0)and the last subframe (i.e., subframe 3) are fractional subframes.Alternatively, as shown in FIG. 6, the factional subframe transmissionterminates at the end of subframe 2. In other words, the factionalsubframe transmission ends at a full subframe.

Additionally, in some embodiments, a transport block size in thefractional subframe may be determined based on the number of theavailable symbols and the data of the transport block size may betransmitted in the subframe.

The transport block size indicates the size of a data block to betransmitted in the fractional subframe transmission. According toembodiments of the present invention, the transport block size may bedetermined in various ways. In some embodiments, the transmitter maydetermine a scaling factor associated with the number of the availablesymbols, and then determine the transport block size based on thescaling factor. The scaling factor may be defined in several ways. Table1 illustrates an example of scaling factors associated with differentnumbers of available symbols.

TABLE 1 Number of available symbols Scaling factor 1, 2, 3 N/A 4 0.25 50.25, 0.375 6 0.375 7 0.375, 0.5 8 0.5, 0.75 9, 10, 11, 12 0.75 13, 14 1

In some embodiments, if the number of the available symbols is 1, 2 or3, the transmitter may use the available symbols to transmit controlinformation of the fractional subframe transmission, and may determinethat the available symbols are not enough for transmitting data afterthe transmission of the control information. In this regard, the scalingfactor may be designed as a value of “N/A”, which indicates that thescaling factor is “not available”. In an exemplary embodiment, if thenumber of the available symbols is 4, the transmitter may determine thatthe associated scaling factor is 0.25. In an exemplary embodiment, ifthe number of the available symbols is 5, the transmitter may determinethat the associated scaling factor is 0.25 or 0.375. In an exemplaryembodiment, if the number of the available symbols is 6, the transmittermay determine that the associated scaling factor is 0.375. In anexemplary embodiment, if the number of the available symbols is 7, thetransmitter may determine that the associated scaling factor is 0.375 or0.5. In an exemplary embodiment, if the number of the available symbolsis 8, the transmitter may determine that the associated scaling factoris 0.5 or 0.75. In an exemplary embodiment, if the number of theavailable symbols is 9, 10, 11 or 12, the transmitter may determine thatthe associated scaling factor is 0.75. In an exemplary embodiment, ifthe number of the available symbols is 13 or 14, the transmitter maydetermine that the associated scaling factor is 1.

In some embodiments, the transport block size may be determined based onthe scaling factor in several ways. By way of example, a first resourceblock number which indicates a number of resource blocks allocated fortransmission may be obtained. For the transmitter, the first resourceblock number may be determined by the transmitter in real time. Then, asecond resource block number may be determined based on the firstresource block number and the scaling factor. In an exemplaryembodiment, the second resource block number may be determined asfollows:N _(PRB)=max{└N _(PRB)′×Factor┘,1}  (2)

wherein N′_(PRB) represents the first resource block number, N_(PRB)represents the second resource block number, Factor represents thescaling factor.

Based on the second resource block number, the transport block size maybe determined. In some embodiments, a transport block size table may beused for determining the transport block size. Table 2 illustrates anexemplary transport block size table.

TABLE 2 MCS 1 2 3 4 5 6 7 8 9 10 0 16 32 56 88 120 152 176 208 224 256 124 56 88 144 176 208 224 256 328 344 2 32 72 144 176 208 256 296 328 376424 3 40 104 176 208 256 328 392 440 504 568 4 56 120 208 256 328 408488 552 632 696 5 72 144 224 328 424 504 600 680 776 872 6 328 176 256392 504 600 712 808 936 1032 7 104 224 328 472 584 712 840 968 1096 12248 120 256 392 536 680 808 968 1096 1256 1384 9 136 296 456 616 776 9361096 1256 1416 1544 10 144 328 504 680 872 1032 1224 1384 1544 1736 11176 376 584 776 1000 1192 1384 1608 1800 2024 12 208 440 680 904 11281352 1608 1800 2024 2280 13 224 488 744 1000 1256 1544 1800 2024 22802536 14 256 552 840 1128 1416 1736 1992 2280 2600 2856 15 280 600 9041224 1544 1800 2152 2472 2728 3112 16 328 632 968 1288 1608 1928 22802600 2984 3240 17 336 696 1064 1416 1800 2152 2536 2856 3240 3624 18 376776 1160 1544 1992 2344 2792 3112 3624 4008 19 408 840 1288 1736 21522600 2984 3496 3880 4264 20 440 904 1384 1864 2344 2792 3240 3752 41364584 21 488 1000 1480 1992 2472 2984 3496 4008 4584 4968 22 520 10641608 2152 2664 3240 3752 4264 4776 5352 23 552 1128 1736 2280 2856 34964008 4584 5160 5736 24 584 1192 1800 2408 2984 3624 4264 4968 5544 599225 616 1256 1864 2536 3112 3752 4392 5160 5736 6200 26 712 1480 22162984 3752 4392 5160 5992 6712 7480

The horizontal direction of Table 2 may correspond to a resource blocknumber, for example, the second resource block number in theembodiments, and the vertical direction may correspond to a Modulationand Coding Scheme (MCS). In the embodiments, when the transmitterdetermines the second resource block number as well as the MCS that isemployed currently, it may determine the transport block size by lookingup the Table 2 based on the second resource block number and the MCS. Byway of example, if the second resource block number is 8, and the MCS is8 the transport block size may be determined as 1096.

It is to be noted that although the dimension of Table 2 is 10×27, it issimplification of 3GPP TS36.213 whose dimension is 34×110. It is furtherto be noted that the above example table is only for the purpose ofillustration, without suggesting any limitations on the subject matterdescribed herein. Any other suitable table may be used in thedetermination of the transport block size.

Reference is now made to FIG. 3, which illustrates a flow chart of amethod 300 for performing fractional subframe transmission at a receiveraccording to an embodiment of the invention. The method 300 may beperformed at a receiver, such as a UE, a D2D receiver, and othersuitable device.

At step S310, a target position is determined from at least onepotential position predefined in a subframe, the fractional subframetransmission starting at the target position.

According to embodiments of the present invention, there may be at leastone potential position predefined in a subframe. In some embodiments, aplurality of potential positions may periodically correspond to symbolsof the subframe, for example according to equation (1). Alternatively,there may be aperiodic configurations of the potential positions. Forinstance, the potential positions may correspond to the symbols 3, 8 and12.

The target position indicates when the fractional subframe transmissionstarts. There may be several ways for the receiver to determine thetarget position based on one or more potential positions predefined inthe subframe. In some embodiments, the transmitter may send an indicatorat the target position to a receiver, wherein the indicator, for examplePCFICH, may indicate a size of control information of the fractionalsubframe transmission. In this way, the target position may be indicatedexplicitly. For the receiver, it may detect the indicator at one of theat least one potential position, for example, denoted as potentialposition 1. In response to that the indicator is detected, the receivermay determine the one of the at least one potential position as thetarget position. Otherwise, the receiver may determine that thispotential position is not the target position and carry out the samedetection on a further potential position, for example potentialposition 2, and so on.

Alternatively, in some embodiments, the transmitter may not send theindicator. In this case, the receiver may make blind decoding forcontrol information of the fractional subframe transmission at one ofthe at least one potential position. In response to that the blinddecoding is success, the receiver may determine the one of the at leastone potential position as the target position.

At step S320, the fractional subframe transmission is received from thetarget position.

In some embodiments, based on the indicator indicating the size ofcontrol information of the fractional subframe transmission, thereceiver may know the size of the control information and accordinglyreceive the control information from the target position.

According to embodiments of the present invention, a number of availablesymbols in the subframe may be determined based on the target position,and the control information and data of the fractional subframetransmission may be received based on the number of the availablesymbols. In some embodiments, during the fractional subframetransmission, the control information may be transmitted before thedata. In this case, the receiver may receive control information priorto the data. In some alternative embodiments, it is possible that thedata is transmitted before the control information. As such, thereceiver may receive the data prior to the control information. Detailswill be discussion with reference to embodiments of FIG. 4.

FIG. 4 illustrates a flow chart of a method 400 for performingfractional subframe transmission at a receiver according to anotherembodiment of the invention. The method 400 may be considered as aspecific implementation of the method 300 described above with referenceto FIG. 3. However, it is noted that this is only for the purpose ofillustrating the principles of the present invention, rather thanlimiting the scope thereof.

At step S410, an indicator is detected at one of the at least onepotential position, the indicator indicating a size of controlinformation of the fractional subframe transmission.

In some embodiments, the transmitter may send an indicator, for examplePCFICH, at the target position to a receiver, to indicate a size ofcontrol information of the fractional subframe transmission. In thiscase, the receiver may detect the indicator at one of the at least onepotential position. At step S420, in response to that the indicator isdetected, the one of the at least one potential position is determinedas the target position. Otherwise, the receiver may detect the indicatorat a further potential position.

At step S430, a number of available symbols in the subframe isdetermined based on the target position.

This step is similar to step S250. In some embodiments, the number ofavailable symbols may be determined based on the target position and thetotal number of symbols in a subframe. By way of example, if there are14 symbols in one subframe, and if the target position corresponds tothe sixth symbol, that is, symbol 5, it may be determined that there are8 available symbols, i.e., symbols 6 to 13. For another example, ifthere are 12 symbols in one subframe, and if the target positioncorresponds to the eighth symbol, that is, symbol 7, it may bedetermined that there are 4 available symbols, i.e., symbols 8 to 11.

At step S440, control information and data of the fractional subframetransmission are received based on the number of the available symbols.

In some embodiments, responsive to the number of the available symbolsis less than or equal to a predetermined threshold, the receiver mayreceive the control information and the data in the available symbolsand a subframe immediately following the subframe. In an exemplaryembodiment, if the number of the available symbols is equal to the sizeof the control information, the receiver may receive the controlinformation in the available symbols of the subframe and receive thedata in a subframe immediately following the subframe. In a furtherexemplary embodiment, if the number of the available symbols is lessthan the size of the control information, the receiver may receive afirst part of the control information in the available symbols of thesubframe and a second part of the control information in a furthersubframe immediately following the subframe, wherein the first part andthe second part constitute the control information. After the controlinformation is received, the receiver may receive the data in thefurther subframe.

Additionally, in some embodiments, a transport block size in thesubframe may be determined based on the number of the available symbols.Then, the data of the transport block size may be received in thesubframe.

The transport block size indicates the size of a data block to betransmitted in the fractional subframe transmission. According toembodiments of the present invention, the transport block size may bedetermined in various ways. In some embodiments, the receiver maydetermine a scaling factor associated with the number of the availablesymbols, and then determine the transport block size based on thescaling factor. The scaling factor may be defined in several ways. Asdiscussed above, Table 1 illustrates an example of scaling factorsassociated with different numbers of available symbols.

In an exemplary embodiment, if the number of the available symbols is 1,2 or 3, the receiver may determine that there is no data transmitted andthere is no need to determine the transport block size. In an exemplaryembodiment, if the number of the available symbols is 4, the receivermay determine that the associated scaling factor is 0.25. In anexemplary embodiment, if the number of the available symbols is 5, thereceiver may determine that the associated scaling factor is 0.25 or0.375. In an exemplary embodiment, if the number of the availablesymbols is 6, the receiver may determine that the associated scalingfactor is 0.375. In an exemplary embodiment, if the number of theavailable symbols is 7, the receiver may determine that the associatedscaling factor is 0.375 or 0.5. In an exemplary embodiment, if thenumber of the available symbols is 8, the receiver may determine thatthe associated scaling factor is 0.5 or 0.75. In an exemplaryembodiment, if the number of the available symbols is 9, 10, 11 or 12,the receiver may determine that the associated scaling factor is 0.75.In an exemplary embodiment, if the number of the available symbols is 13or 14, the receiver may determine that the associated scaling factor is1.

In some embodiments, the transport block size may be determined based onthe scaling factor in several ways. By way of example, a first resourceblock number which indicates a number of resource blocks allocated fortransmission may be obtained. For the receiver, the first resource blocknumber may be notified by the transmitter. Then, a second resource blocknumber may be determined based on the first resource block number andthe scaling factor. In an exemplary embodiment, the second resourceblock number may be determined according to equation (2). Based on thesecond resource block number, the transport block size may bedetermined. In some embodiments, a transport block size table, forexample Table 2, may be used for determining the transport block size.In particular, if the receiver determines the second resource blocknumber as well as the MCS which is employed currently, it may determinethe transport block size by looking up the Table 2.

FIG. 7 illustrates a block diagram of an apparatus 700 for performingfractional subframe transmission according to embodiments of theinvention. In accordance with embodiments of the present invention, theapparatus 700 may be implemented at a transmitter, for example, a BS, aD2D transmitter or any other applicable device.

As shown, the apparatus 700 comprises: a first determining unit 710configured to in response to detecting that a channel becomes available,determine a target position from at least one potential positionpredefined in a subframe; and a performing unit 720 configured toperform the fractional subframe transmission from the target position.

According to embodiments of the present invention, the first determiningunit 710 may comprise: a potential position detecting unit configured todetect whether a current position is a potential position; and a firsttarget position determining unit configured to responsive to that thecurrent position is a potential position, determine the potentialposition as the target position, and responsive to that the currentposition is not a potential position, transmit a channel occupationsignal from the current position until a potential position anddetermine the potential position as the target position.

According to embodiments of the present invention, each of the at leastone potential position may correspond to a symbol of the subframeperiodically or aperiodically.

According to embodiments of the present invention, the performing unit720 may comprise: a sending unit configured to send an indicator at thetarget position, the indicator indicating a size of control informationof the fractional subframe transmission.

According to embodiments of the present invention, the performing unit720 may comprise: a first available symbol number determining unitconfigured to determine a number of available symbols in the subframebased on the target position; and a transmitting unit configured totransmit control information and data of the fractional subframetransmission from the target position based on the number of theavailable symbols.

In some embodiments, the transmitting unit may be further configured to:responsive to the number of the available symbols is less than or equalto a predetermined threshold, transmit the control information and thedata in the available symbols and a subframe immediately following thesubframe.

In some embodiments, the transmitting unit may comprise: a sizedetermining unit configured to determine a transport block size in thesubframe based on the number of the available symbols, wherein thetransmitting unit may be further configured to transmit the data of thetransport block size in the subframe.

According to embodiments of the present invention, the performing unit720 may comprise: a scheduling information obtaining unit configured toobtain preconfigured scheduling information associated with the targetposition, wherein the performing unit may be further configured toperform the fractional subframe transmission based on the preconfiguredscheduling information.

FIG. 8 illustrates a block diagram of an apparatus 800 for performingfractional subframe transmission according to embodiments of theinvention. In accordance with embodiments of the present invention, theapparatus 800 may be implemented at a receiver, for example, a cellularUE, a D2D receiver or any other applicable device.

As shown, the apparatus 800 comprises: a second determining unit 810configured to determine a target position from at least one potentialposition predefined in a subframe, the fractional subframe transmissionstarting at the target position; and a receiving unit 820 configured toreceive the fractional subframe transmission from the target position.

According to embodiments of the present invention, the seconddetermining unit 810 may comprise: an indicator detecting unitconfigured to detect an indicator at one of the at least one potentialposition, the indicator indicating a size of control information of thefractional subframe transmission; and a second target positiondetermining unit configured to in response to that the indicator isdetected, determine the one of the at least one potential position asthe target position.

According to embodiments of the present invention, the seconddetermining unit 810 may comprise: a decoding unit configured to makeblind decoding for control information of the fractional subframetransmission at one of the at least one potential position; and a thirdtarget position determining unit configured to in response to that theblind decoding is success, determine the one of the at least onepotential position as the target position.

According to embodiments of the present invention, each of the at leastone potential position may correspond to a symbol of the subframeperiodically or aperiodically.

According to embodiments of the present invention, the receiving unit820 may comprise: a second available symbol number determining unitconfigured to determine a number of available symbols in the subframebased on the target position, wherein the receiving unit may be furtherconfigured to receive control information and data of the fractionalsubframe transmission based on the number of the available symbols.

According to embodiments of the present invention, the receiving unit820 may be further configured to responsive to the number of theavailable symbols is less than or equal to a predetermined threshold,receive the control information and the data in the available symbolsand a subframe immediately following the subframe.

According to embodiments of the present invention, the receiving unit820 may comprise: a size determining unit configured to determine atransport block size in the subframe based on the number of theavailable symbols, wherein the receiving unit may be further configuredto receive the data of the transport block size in the subframe.

It is also to be noted that the apparatuses 700 and 800 may berespectively implemented by any suitable technique either known atpresent or developed in the future. Further, a single device shown inFIG. 7 or FIG. 8 may be alternatively implemented in multiple devicesseparately, and multiple separated devices may be implemented in asingle device. The scope of the present invention is not limited inthese regards.

It is noted that the apparatus 700 may be configured to implementfunctionalities as described with reference to FIGS. 1-2, and theapparatus 800 may be configured to implement functionalities asdescribed with reference to FIGS. 3-4. Therefore, the features discussedwith respect to the method 100 or 200 may apply to the correspondingcomponents of the apparatus 700, and the features discussed with respectto the method 300 or 400 may apply to the corresponding components ofthe apparatus 800. It is further noted that the components of theapparatus 700 or the apparatus 800 may be embodied in hardware,software, firmware, and/or any combination thereof. For example, thecomponents of the apparatus 700 or the apparatus 800 may be respectivelyimplemented by a circuit, a processor or any other appropriate device.Those skilled in the art will appreciate that the aforesaid examples areonly for illustration not limitation.

In some embodiment of the present disclosure, the apparatus 700 or theapparatus 800 may comprise at least one processor. The at least oneprocessor suitable for use with embodiments of the present disclosuremay include, by way of example, both general and special purposeprocessors already known or developed in the future. The apparatus 700or the apparatus 800 may further comprise at least one memory. The atleast one memory may include, for example, semiconductor memory devices,e.g., RAM, ROM, EPROM, EEPROM, and flash memory devices. The at leastone memory may be used to store program of computer executableinstructions. The program can be written in any high-level and/orlow-level compliable or interpretable programming languages. Inaccordance with embodiments, the computer executable instructions may beconfigured, with the at least one processor, to cause the apparatus 700to at least perform according to the method 100 or 200 as discussedabove, or to cause the apparatus 800 to at least perform according tothe method 300 or 400 as discussed above.

Based on the above description, the skilled in the art would appreciatethat the present disclosure may be embodied in an apparatus, a method,or a computer program product. In general, the various exemplaryembodiments may be implemented in hardware or special purpose circuits,software, logic or any combination thereof. For example, some aspectsmay be implemented in hardware, while other aspects may be implementedin firmware or software which may be executed by a controller,microprocessor or other computing device, although the disclosure is notlimited thereto. While various aspects of the exemplary embodiments ofthis disclosure may be illustrated and described as block diagrams,flowcharts, or using some other pictorial representation, it is wellunderstood that these blocks, apparatus, systems, techniques or methodsdescribed herein may be implemented in, as non-limiting examples,hardware, software, firmware, special purpose circuits or logic, generalpurpose hardware or controller or other computing devices, or somecombination thereof.

The various blocks shown in FIGS. 1-4 may be viewed as method steps,and/or as operations that result from operation of computer programcode, and/or as a plurality of coupled logic circuit elementsconstructed to carry out the associated function(s). At least someaspects of the exemplary embodiments of the disclosures may be practicedin various components such as integrated circuit chips and modules, andthat the exemplary embodiments of this disclosure may be realized in anapparatus that is embodied as an integrated circuit, FPGA or ASIC thatis configurable to operate in accordance with the exemplary embodimentsof the present disclosure.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anydisclosure or of what may be claimed, but rather as descriptions offeatures that may be specific to particular embodiments of particulardisclosures. Certain features that are described in this specificationin the context of separate embodiments can also be implemented incombination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesub-combination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asub-combination or variation of a sub-combination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the embodiments described above should not be understoodas requiring such separation in all embodiments, and it should beunderstood that the described program components and systems cangenerally be integrated together in a single software product orpackaged into multiple software products.

Various modifications, adaptations to the foregoing exemplaryembodiments of this disclosure may become apparent to those skilled inthe relevant arts in view of the foregoing description, when read inconjunction with the accompanying drawings. Any and all modificationswill still fall within the scope of the non-limiting and exemplaryembodiments of this disclosure. Furthermore, other embodiments of thedisclosures set forth herein will come to mind to one skilled in the artto which these embodiments of the disclosure pertain having the benefitof the teachings presented in the foregoing descriptions and theassociated drawings.

Therefore, it is to be understood that the embodiments of the disclosureare not to be limited to the specific embodiments disclosed and thatmodifications and other embodiments are intended to be included withinthe scope of the appended claims. Although specific terms are usedherein, they are used in a generic and descriptive sense only and notfor purpose of limitation.

What is claimed is:
 1. A method performed by a user equipment (UE), themethod comprising: acknowledging a plurality of potential positionswhere a downlink transmission starts on an unlicensed spectrum; andreceiving, from a base station, the downlink transmission starting froma target position on the unlicensed spectrum, wherein, the targetposition is any one of the plurality of potential positions, and theplurality of potential positions corresponds to a plurality of positionsthat are equally spaced with a periodic interval of a duration of aplurality of symbols, wherein the duration of the plurality of symbolsis shorter than a duration of a subframe.
 2. The method of claim 1,wherein the plurality of positions includes symbol 0 in a subframe. 3.The method of claim 1, wherein the downlink transmission ends at asymbol of a subframe with symbols occupied and other symbols notoccupied.
 4. The method of claim 1, wherein the downlink transmissionstarts in response to the base station detecting that a channel on theunlicensed spectrum is idle.
 5. The method of claim 1, wherein controlinformation is received at the target position.
 6. A method performed bya base station, the method comprising: acknowledging a plurality ofpotential positions where a downlink transmission starts on anunlicensed spectrum; performing the downlink transmission to a userequipment (UE), starting from a target position on the unlicensedspectrum, wherein, the target position is any one of a plurality ofpotential positions, and the plurality of potential positionscorresponds to a plurality of positions that are equally spaced with aperiodic interval of a duration of a plurality of symbols, wherein theduration of the plurality of symbols is shorter than a duration of asubframe.
 7. The method of claim 6, wherein the plurality of positionsincludes symbol 0 in a subframe.
 8. The method of claim 6, wherein thedownlink transmission ends at a symbol of a subframe with symbolsoccupied and other symbols not occupied.
 9. The method of claim 6,wherein the downlink transmission starts in response to the base stationdetecting that a channel on the unlicensed spectrum is idle.
 10. Themethod of claim 6, wherein control information is transmitted at thetarget position.
 11. A user equipment (UE), the UE comprising a receiverconfigured to: acknowledge a plurality of potential positions where adownlink transmission starts on an unlicensed spectrum; and receive,from a base station, the downlink transmission starting from a targetposition on an unlicensed spectrum, wherein, the target position is anyone of the plurality of potential positions, and the plurality ofpotential positions corresponds to a plurality of positions that areequally spaced with a periodic interval of a duration of a plurality ofsymbols, wherein the duration of the plurality of symbols is shorterthan a duration of a subframe.